Screw socket

ABSTRACT

An Edison-type lamp socket comprises a cylindrical insulating housing receivably mounting a contact shell formed of a pair of matching half sections which are connected at one of their respective ends by a pair of parallel spaced spring straps which allow the contact shell to expand from its unloaded generallyelliptical shape into circular conformity with the lamp base when the latter is threaded into the socket to provide firm resilient circumferential contact with the lamp base.

Unite States Patent [1 1 [111 3,827,003

Sullivan July 30, 1974 SCREW SOCKET 2,292,242 8/1942 Sagona 339/69 ux 2 l9 [75] Inventor: James Suuwan, Eastchester 121922 333/ 1 45 1 2 [73] Assignee: Kulka Electric Corp., Mount Vernon, N.Y. Primary ExaminerBobby R. Gay Assistant Examiner-Lawrence J. Staab [22] Ffled: May 1973- Attorney, Agent, or FirmFrank R. Trifari [21] Appl. N0.: 358,479

[57] ABSTRACT 52 13.5. CI. 339/180, 339/199 An -WP 9 899M comprises a cylindrical [51 Int. Cl. l-lOlr 17/20 insulating housing receivably mounting 9 999mm shell 5 n w f Search H 339 L, 9 7 7 7 formed of a pair of matching half sections which are 74 7 L, 30 99 255 RT, 5 C connected at one of their respective ends by a pair of 25 RT, 25 R parallel spaced spring straps which allow the contact shell to expand from its unloaded generally-elliptical [56] References Cited shape into circular conformity with the lamp base UNn-CD STATES PATENTS when the latter is threaded into the socket to provide I firm resilient circumferential contact with the lamp 1.048279 I2/l9l2 Ben amin 339/l80 X base I l,5l9 774 12/1924 Ebcrhardt.... 339/73 1.780.832 l1/l930 McAdums ct al... 339/69 10 Claims, 5 Drawing Figures SCREW SOCKET BACKGROUND OF THE INVENTION The present invention relates to electrical lamp screw sockets and more particularly to Edison-type lamp sockets for mounting high power lamps, such as mercury lamps.

Heavy-duty lamps operating at high current levels are generally of larger and heavier construction than ordinary incandescent lamps. It is therefore important that such a high power lamp be firmly secured in its socket and that the contact shell and center contact of the socket provide reliable electrical contact with a minimum of contact resistance between the lamp base and its socket, even under adverse operating conditions. At the same time, the shell structure should also provide a resilient mounting to absorb mechanical vibration or shock which might otherwise cause breakage or momentary interruption in the electrical circuit connection between the lamp and the socket contacts.

BRIEF DESCRIPTION OF THE INVENTION It is therefore an object of the present invention to provide an Edison-type lamp socket which provides a firm resilient mounting for high-current, heavy duty lamps.

It is another object of the present invention to provide an Edison-type lamp socket which ensures reliable low-resistance electrical contact with a high-current heavy duty lamp under mechanical vibration and shock conditions.

In accordance with the principles of the present invention, there is provided a lamp screw socket adapted to receive a threaded lamp base. The socket includes a threaded contact shell comprising a pair of matching shell half sections integrally connected at one of their respective ends by spring means, the other free ends of the shell sections being held in abutment when the contact shell is mounted in the socket housing. The shell sections are operative to expand the diametrical gap of the contact shell to receive the lamp base when it is threaded thereinto to provide a firm resilient mounting for the lamp base.

Further objects, features and advantages of the present invention will become apparent upon consideration of the following description in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is an exploded perspective view showing the socket housing and the contact shell received therein;

FIG. 2 is a top plan view of the socket in the assembled condition;

FIG. 3 is a cross sectional view taken along the line 33 of FIG. 2;

FIG. 4 is a front elevational view of the center DETAILED DESCRIPTION OF THE INVENTION Referring to the drawings, and in particular to FIGS. 1 and 2 thereof, the socket of the present invention comprises a cylindrical insulating socket housing 10 having a cylindrical bore 12 for receiving a metal contact shell 14 in assembly therewith.

Contact shell 14 comprises a pair of arcuate matching half shell sections 16 and 18 connected together at one end by a pair of thin metal parallel spaced spring straps 20 and 22. The other free ends of half sections 16 and I8 terminate in outwardly projecting confronting flange sections 24 and 26.

Shell half sections 16 and 18 are grooved as indicated by numerals 28 to form a thread to receive the threaded base of a light bulb when shell 14 is fixedly seated in socket housing 10 as described hereinafter.

The connected ends of shell half-sections l6 and 18 respectively terminate in integrally formed narrow strips 30 and 32. The opposite ends of strip 30 are bent outwardly with respect to shell 14 to form positioning flanges 34 and 36 while positioning flanges 38 and 40 are similarly formed with respect to strip 32. Flexible spring straps 20 and 22 are arcuately bent outwardly with respect to shell 14 to form half-loops and are integrally formed with strips 30 and 32.

Flange section 24 comprises coplanar upper and lower flanges 40 and 42 spaced from each other to fonn a gap 41 while flange section 26 includes coplanar upper and lower spaced flanges 44 and 46 which respectively confront flanges 40 and 42. An alignment lug 48 is formed between flanges 44 and 46 and extends slightly outwardly from the plane of flanges 44 and 46. Lug 48 and gap 41 are suitably sized so that when flanges 40 and 42 are brought into confronting relationship with flanges 44 and 46 respectively when shell 14 is received in housing 10, lug 48 will be received in gap 41 in close fitting relationship.

Projecting downwardly from the lower edge of shell sections 16 and 18 approximately midway of their lengths respectively, are L-shaped terminal legs 50 and 52. Legs 50 and 52 terminate in right-angled lugs 54 and 56 having threaded apertures 58 and 60 respectively for receiving screws 62 and 64 for mounting shell 14 in housing 10, as explained hereinafter.

Referring to FIGS. 1-3, housing 10 has a generally cylindrical bore wall 66 extending from the housing upper open end 68 down to the housing base wall 70. Bore wall 66 is provided with a vertical retaining groove 72 and a wide positioning slot 74, diametrically opposite to retaining groove 72. Retaining groove 72 and positioning slot 74 extend vertically upward from a position slightly above the upper surface of housing width of retaining groove 72 may be tapered downwardly from open end 68 to facilitate insertion of shell 14 into housing 10.

Housing base is provided with an elongated radial recess 76 for receiving a spring type center contact 78 shown in FIGS. 2-5. A pair of diametrically opposed recesses 81 and 83 are located in housing base 70 for receiving terminal lugs 54 and 56 respectively.

Center contact 78 is in the form of a bent bracket having a pair of folded arms 84 and 86 with a compression coil spring 88 fixedly secured between the terminal ends thereof. The upper contact arm 84 tenninates in a circular lug 84a having a central circular depression 90 in the upper surface thereof for receiving the central lamp base contact. Circular depression 90 forms a nipple 92 on the under surface of upper contact arm 84. Lower contact arm 86 is provided with a threaded circular aperture 94 for receiving a mounting screw 96 therein from the bottom side thereof through aperture 94 which forms a surrounding threaded rim 98 on the upper surface of contact arm 86.

Coil spring 88 is assembled to center contact 78 by compressing spring 88 and locating the end coils thereof over rim 98 and nipple 92 whereby compression loaded spring 88 urges contact arms 84 and 86 apart against the spring action of arms 84 and 86. Compression coil spring 88 is suitably sized and compressed prior to assembly with contact arms 84 and 86 so that spring 88 is maintained firmly in position therebetween by retaining rim 98 and nipple 92.

Center contact 78 is connected to housing base 70 by locating lower contact arm 86 in recess 76 so that aperture 94 is in register with a through aperture 100 centrally located in the housing base wall 70 and fastening contact arm 86 to base wall 70 by means of mounting screw 96. A center contact lead wire 102 may be electrically connected to center contact 78 by soldering one exposed end thereof to the upper surface of lower contact arm 86 and running lead wire 102 through adjoining housing base aperture 104 to emerge at the underside of housing base wall 70.

In assembling shell 14 with housing 10, shell sections 16 and 18 are pressed together by a suitable tool gripping opposing flange sections 24 and 26 into confronting relationship and compressing spring straps and 22 whereby flanges 40 and 42 abut opposing flanges 44 and 46 respectively and lug 48 is received by gap 41 in close fitting relationship. Shell 14 in this closed condition is inserted into housing bore 12 so that abutting flange sections 24 and 26 slide downwardly in retaining groove 72 while positioning flanges 34, 36, 38 and 40 slide downwardly in positioning slot 74. Shell 14 is thus inserted in housing bore 12 until terminal lugs 54 and 56 are seated in recesses 81 and 83 respectively.

When shell 14 is released from its gripping tool, retaining groove 72 will keep flange sections 24 and 26 in confronting relationship and positioning flanges 34, 36, 38 and 40 will be spring urged apart and against the opposite side walls 740 and 74b of positioning slot 74 under the spring action of spring straps 20 and 22.

A lead wire 106 may be electrically connected to shell 14 by soldering an exposed end thereof to a terminal leg 52 and running lead wire 106 through aperture 108 which adjoins recess 83 in base wall 66.

Shell 14 is then fixedly secured to housing 10 by mounting screws 62 and 64 which are inserted through base apertures 110 and 112 and terminal lug apertures 58 and 60.

When thus mounted in housing 10, shell 14, as viewed from the open upper end of housing 10 and shown in FIG. 2, will be generally elliptical in shape wherein the minor axis thereof between opposite shell sections 16 and 18 is slightly less than the major axis thereof as measured between flange sections 24, 26 and straps 20, 22. Since housing bore 12 is substantially cylindrical there will be some clearance between the outer surfaces of shell sections 16 and 18 and the bore wall of shell 10, as illustrated in FIG. 2. When the lamp (not shown) is threaded intoshell 14, the circular base thereof will'distort shell sections 16 and 18 thereby providing a secure grip of the lamp base in the socket, whereby shell 14 will adopt a generally circular shape conforming to the circular shape of the lamp base.

An important feature of the present invention resides in the function of spring straps 20 and 22 in providing a spring loaded gripping action of shell sections 16 and 18 when the lamp contact base is thus screw threaded in socket shell 14. Thus, as shell sections 16 and 18 are distended when the lamp base is threaded in shell 14, half-looped straps 20 and 22 slightly flatten to permit the outward radial movement of sections 16 and 18 to accommodate the circular lamp contact base. When the lamp contact base is unscrewed from socket shell 14, shell 14 will resume its generally elliptical shape and spring straps 20 and 22 will revert to its half-looped condition, as shown in FIG. 2.

Another important feature of the present invention resides in the operation of central contact 78 to provide firm spring loaded contact with the electrical contact area of the lamp contact base. Thus, as the lamp contact base is screw threaded into shell socket 14 upper contact arm 84 will be correspondingly depressed against the action of compression spring 88 which maintains a firm spring loaded contact between contact arm 84 and the lamp base contact which seats in contact arm depression 90. Such firm contact pressure between the lamp base contact area and contact arm 84 minimizes contact resistance between the lamp base contact and socket contact 78 and tends to overcome the deleterious effects of any corrosion or deposition of foreign matter which commonly form on electrical contact surfaces.

While a preferred embodiment of the invention has been shown and described herein, it is obvious that numerous omissions, changes and additions may be made in such embodiment without departing from the spirit and scope of the invention.

What is claimed is:

1. A lamp screw socket for receiving a threaded lamp base comprising, a threaded contact shell for receiving the said threaded lamp base, and a socket housing having a generally cylindrical bore with an open upper end for receivably mounting said contact shell, said contact comprising a pair of matching shell half sections connected at one of their respective ends by spring means, the other free ends of said shell sections being fixedly secured in close confronting relationship.

2. A lamp screw socket as defined in claim 1 wherein said contact shell assumes a generally elliptical shape when said lamp base is removed therefrom wherein the minor diameter thereof measured between the respective mid points of said shell sections in slightly less than the diameter of said lamp base.

3. A lamp screw socket as defined in claim 2 wherein said spring means allows said contact shell to expand diametrically along the axis of its minor diameter when said lamp base is threaded therein, whereby said contact shell assumes a generally circular shape in firm circumferential contact with said lamp base.

4. A lamp screw locket as defined in claim 3 wherein said spring means comprises a pair of parallel spaced horizontal straps bent outwardly with respect to said contact shell to form half loops.

5. A lamp screw socket as defined in claim 4 wherein the bore wall of said socket housing has a retaining groove therein generally parallel to the longitudinal axis of said housing bore, said free ends of said shell sections respectively terminating in flange portions extending outwardly with respect to said shell contact, said flange sections being fitted in said retaining groove in close confronting relationship.

6. A lamp screw socket as defined in claim 5 wherein said bore wall has a positioning slot extending generally parallel to the axis of said housing bore, and the connected ends of said shell sections respectively terminate in outwardly extending positioning flanges which are urged apart and against the opposite side walls of terminal ends of said folded arms.

9. A lamp screw socket as defined in claim 8 wherein said pair of folded arms comprises an upper and a lower arm, said upper arm having a central circular depression formed in the upper surface of its terminal end for receiving the lamp base center contact, said lamp base depresses said upper arm against the action of said compression spring when said lamp base is screwthreaded into said shell contact.

10. A lamp screw socket as defined in claim 9 wherein said center contact lower arm is fixedly secured at its terminal end to said housing base wall, said upper arm having a nipple formed in the undersurface of its terminal end for receiving the upper end coil of said compression spring, and said center contact lower arm having a circular rim formed in the upper surface of its terminal end for receiving the lower end coil of said compression spring thereby retaining said spring in compression between the respective terminal ends of said upper and lower center contact arms. 

1. A lamp screw socket for receiving a threaded lamp base comprising, a threaded contact shell for receiving the said threaded lamp base, and a socket housing having a generally cylindrical bore with an open upper end for receivably mounting said contact shell, said contact comprising a pair of matching shell half sections connected at one of their respective ends by spring means, the other free ends of said shell sections being fixedly secured in close confronting relationship.
 2. A lamp screw socket as defined in claim 1 wherein said contact shell assumes a generally elliptical shape when said lamp base is removed therefrom wherein the minor diameter thereof measured between the respective mid points of said shell sections in slightly less than the diameter of said lamp base.
 3. A lamp screw socket as defined in claim 2 wherein said spring means allows said contact shell to expand diametrically along the axis of its minor diameter when said lamp base is threaded therein, whereby said contact shell assumes a generally circular shape in firm circumferential contact with said lamp base.
 4. A lamp screw locket as defined in claim 3 wherein said spring means comprises a pair of parallel spaced horizontal straps bent outwardly with respect to said contact shell to form half loops.
 5. A lamp screw socket as defined in claim 4 wherein the bore wall of said socket housing has a retaining groove therein generally parallel to the longitudinal axis of said housing bore, said free ends of said shell sections respectively terminating in flange portions extending outwardly with respect to said shell contact, said flange sections being fitted in said retaining groove in close confronting relationship.
 6. A lamp screw socket as defined in claim 5 wherein said bore wall has a positioning slot extending generally parallel to the axis of said housing bore, and the connected ends of said shell sections respectively terminate in outwardly extending positioning flanges which are urged apart and against the opposite side walls of said positioning slot under the spring action of said half-looped straps.
 7. A lamp screw socket as defined in claim 6 wherein said socket housing comprises a base wall formed at the bottom end of said bore wall, and a spring loaded center contact fixedly secured to said base wall for making electrical contact with said lamp base.
 8. A lamp screw socket as defined in claim 7 wherein said center contact comprises a bent bracket having a pair of folded arms and a compression coil spring having its opposite end coils respectively secured to the terminal ends of said folded arms.
 9. A lamp screw socket as defined in claim 8 wherein said pair of folded arms comprises an upper and a lower arm, said upper arm having a central circular depression formed in the upper surface of its terminal end for receiving the lamp base center contact, said lamp base depresses said upper arm against the action of said compression spring when said lamp base is screw-threaded into said shell contact.
 10. A lamp screw socket as defined in claim 9 wherein said center contact lower arm is fixedly secured at its terminal end to said housing base wall, said upper arm having a nipple formed in the undersurface of its terminal end for receiving the upper end coil of said compression spring, and said center contact lower arm having a circular rim formed in the upper surface of its terminal end for receiving the lower end coil of said compression sprIng thereby retaining said spring in compression between the respective terminal ends of said upper and lower center contact arms. 